My solution to this is that I accept the other job offer, and I don't quit until the night before I start my first day in the new one. As a result I've never spent a single day unemployed. If something I'm counting on doesn't come through I'm already at my backup plan.
If companies won't be loyal to us in this way, why do we owe any loyalty to them in return?
I mean it's not really needed in Europe where true legal rights exist for employees, right?
This is more of a "only in the USA" kind of thing.